Citing the much larger number of environments (10 in PGR4, vs. five in PGR3), the article lauds the new lighting system over having two "fixed" times of day (and therefore two sets of textures). "DVD size is absolutely not [their emphasis] a factor that we consider when designing our games ... and PGR4 is no exception. DVD9 gives us more than we need to create a fabulous experience for you guys," it said, later adding, "we've never had to cut content to fit on the disc, and we probably never will." Maybe it wasn't cut, but we're pretty sure they would've planned for more environments on a larger disc.
The original comment, which sparked the discussion, was, "Whilst this wasn't a problem for our dev team, it was a problem fitting all this data onto a single DVD." While we applaud the ingenuity of a new lighting system, they did say the data for two textures could not fit.
Should the extra content situation ever arise, we're sure they could make it downloadable on Xbox Live, possibly for a fee. Bizarre's biggest concern right now should be including a new Geometry Wars onto the disc -- if it's not there, there's going to be heck to pay. Heck, I tell you.